1. Field of Invention
The present invention relates to a semiconductor process. More particularly, the present invention relates to a technology to detection of a method for decapsulating a package.
2. Description of Related Art
Integrated circuit (IC) packaging is a way of separating the IC chips on a wafer after the front-end semiconductor fabrication process, connecting the chips to individual lead frames and encapsulating the chips for a better protection. At present, the most common chip packaging technique includes the flip chip interconnect technology. The method includes providing conductive bumps on the input/output (I/O) contacts of a chip and then flipping over the chip so that the bumps can directly contact a substrate. The major advantages of the flip chip bonding technique are small area occupation, high lead count, short interconnect, low inductance and easy-to-control noise level. As a result, the flip chip package is particularly suitable for producing high-speed, high-performance, light and compact device.
In order to perform a failure analysis on the package or to conduct a rework process on the package, it is necessary to decapsulate the package to be a chip without having the solder bumps and the underfill thereon. The most common method for removing the underfill and the solder bumps is to grind or polish away the substrate from the chip and remove the underfill and the solder bumps as well. However, the surface of the chip is easily damaged during the grinding or polishing process. Therefore, the electrical probing during the failure inspection is seriously affected by the grinding or polishing result. Furthermore, by using the grinding or polishing process, the solder bumps are removed together with the underfill. Therefore, when the underfill is the only part needed to be rework, it is hard to remove the underfill but leave the solder bumps on the chip by using the grinding or polishing process.
In order to remove the underfill without removing the solder bumps or to remove the solder bumps without damaging the underfill, the industry develops several ways. However, none of the methods can remove the underfill completely without leaving the underfill residual on the chip or can remove the underfill completely without damaging the solder bumps. Furthermore, none of the methods can remove the solder bumps without damaging the metal pads on the chip or can remove the solder bumps without spending a lot of money.